1. Field of the Invention
The present invention relates to a novel 1,4-dihydropyridine-5-phosphonic acid cyclic propylene ester, a process for the preparation thereof, and an antihypertensive agent or coronary or cerebral vasodilator composition containing the novel ester or its pharmaceutically acceptable salt.
2. Description of the Prior Art
1,4-Dihydropyridines-5-phosphonic acid esters are known to be useful for the medical treatment of coronary heart diseases, cerebral diseases, hypertension or arrhythmia, as they are capable of inhibiting the contraction of smooth muscle and cardiac muscle by calcium antagonistic effects. (See European Patent Publications EP 0159040A and EP 0121117A which corresponds to U.S. Pat. No. 4,535,073.)